Human body fasting mechanisms

I was reading a bit about CRTC3 as a mechanism for slowing fat burn in times of famine. I don't have time to finish the article but I wanted to see if anybody knew anything about it, and whether it is prevalent in humans, and if so what is its effect on intermittent fasting? Does it activate only in extended fasts as we enter the protein-sparing state? And how does it relate to being in a ketogenic metabolism versus a glycolytic?